Out of plane optical conductivity in d-wave superconductors

We study theoretically the out of plane optical conductivity of d-wave superconductors in the presence of impurities at T=0K. Unlike the usual approach, we assume that the interlayer quasi-particle transport is due to coherent tunneling. The present model describes the T^2 dependence of the out of plane superfluid density observed in YBCO and Tl2201 for example. In the optical conductivity there is no Drude peak in agreement with experiment, and the interlayer Josephson tunneling is also assured in this model. In the unitary limit we predict a step like behaviour around omega=Delta in both the real and imaginary part of the optical conductivity.Comment: 7 pages, 7 figure

Nonlinear current-induced forces in Si atomic wires

We report first-principles calculations of current-induced forces in Si atomic wires as a function of bias and wire length. We find that these forces are strongly nonlinear as a function of bias due to the competition between the force originating from the scattering states and the force due to bound states. We also find that the average force in the wire is larger the shorter the wire, suggesting that atomic wires are more difficult to break under current flow with increasing length. The last finding is in agreement with recent experimental data.Comment: 4 figure

The Expression and Roles of Nde1 and Ndel1 in the Adult Mammalian Central Nervous System

Open Access funded by Wellcome Trust Under a Creative Commons license Acknowledgments We thank Prof Angelo Sementilli, Department of Pathology, Universidade Metropolitana de Santos, SP, Brazil, for the human sample collection. This study is funded by Scottish Universities Life Sciences Alliance (HR07019 to S. Shen and C.D. McCaig), Medical Research Scotland (384 FRG to B. Lang, United Kingdom), Tenovus Scotland (G12/25 to B. Lang), Sino-UK Higher Education Research Partnership for PhD Studies (C.D. McCaig and Y.Q. Ding) and Wellcome Trust (WT081633MA-NCE to P.J.A. McCaffery, United Kingdom).Peer reviewedPublisher PD

Mechanisms for electron transport in atomic-scale one-dimensional wires: soliton and polaron effects

We study one-electron tunneling through atomic-scale one-dimensional wires in the presence of coherent electron-phonon (e-ph) coupling. We use a full quantum model for the e-ph interaction within the wire with open boundary conditions. We illustrate the mechanisms of transport in the context of molecular wires subject to boundary conditions imposing the presence of a soliton defect in the molecule. Competition between polarons and solitons in the coherent transport is examined. The transport mechanisms proposed are generally applicable to other one-dimensional nanoscale systems with strong e-ph coupling.Comment: 7 pages, 4 figures, accepted for publication in Europhys. Let

Scanning tunneling spectroscopy characterization of the pseudogap and the x = 1/8 anomaly in La2-xSrxCuO4 thin films

Using scanning tunneling spectroscopy we examined the local density of states of thin c-axis La2-xSrxCuO4 films, over wide doping and temperature ranges. We found that the pseudogap exists only at doping levels lower than optimal. For x = 0.12, close to the 'anomalous' x = 1/8 doping level, a zero bias conductance peak was the dominant spectral feature, instead of the excepted V- shaped (c-axis tunneling) gap structure. We have established that this surprising effect cannot be explained by tunneling into (110) facets. Possible origins for this unique behavior are discussed.Comment: 15 pages, 6 figure

Precipitation and latent heating distributions from satellite passive microwave radiometry. Part I: improved method and uncertainties

A revised Bayesian algorithm for estimating surface rain rate, convective rain proportion, and latent heating profiles from satellite-borne passive microwave radiometer observations over ocean backgrounds is described. The algorithm searches a large database of cloud-radiative model simulations to find cloud profiles that are radiatively consistent with a given set of microwave radiance measurements. The properties of these radiatively consistent profiles are then composited to obtain best estimates of the observed properties. The revised algorithm is supported by an expanded and more physically consistent database of cloud-radiative model simulations. The algorithm also features a better quantification of the convective and nonconvective contributions to total rainfall, a new geographic database, and an improved representation of background radiances in rain-free regions. Bias and random error estimates are derived from applications of the algorithm to synthetic radiance data, based upon a subset of cloud-resolving model simulations, and from the Bayesian formulation itself. Synthetic rain-rate and latent heating estimates exhibit a trend of high (low) bias for low (high) retrieved values. The Bayesian estimates of random error are propagated to represent errors at coarser time and space resolutions, based upon applications of the algorithm to TRMM Microwave Imager (TMI) data. Errors in TMI instantaneous rain-rate estimates at 0.5°-resolution range from approximately 50% at 1 mm h−1 to 20% at 14 mm h−1. Errors in collocated spaceborne radar rain-rate estimates are roughly 50%–80% of the TMI errors at this resolution. The estimated algorithm random error in TMI rain rates at monthly, 2.5° resolution is relatively small (less than 6% at 5 mm day−1) in comparison with the random error resulting from infrequent satellite temporal sampling (8%–35% at the same rain rate). Percentage errors resulting from sampling decrease with increasing rain rate, and sampling errors in latent heating rates follow the same trend. Averaging over 3 months reduces sampling errors in rain rates to 6%–15% at 5 mm day−1, with proportionate reductions in latent heating sampling errors

Particle-Number Reprojection in the Shell Model Monte Carlo Method: Application to Nuclear Level Densities

We introduce a particle-number reprojection method in the shell model Monte Carlo that enables the calculation of observables for a series of nuclei using a Monte Carlo sampling for a single nucleus. The method is used to calculate nuclear level densities in the complete $(pf+g_{9/2})$-shell using a good-sign Hamiltonian. Level densities of odd-A and odd-odd nuclei are reliably extracted despite an additional sign problem. Both the mass and the $T_z$ dependence of the experimental level densities are well described without any adjustable parameters. The single-particle level density parameter is found to vary smoothly with mass. The odd-even staggering observed in the calculated backshift parameter follows the experimental data more closely than do empirical formulae.Comment: 14 pages, 4 eps figures included, RevTe

A high fibered power of a family of varieties of general type dominates a variety of general type

We prove the following theorem: Fibered Power Theorem: Let X\rar B be a smooth family of positive dimensional varieties of general type, with $B$ irreducible. Then there exists an integer $n>0$, a positive dimensional variety of general type $W_n$, and a dominant rational map X^n_B \das W_n.Comment: Latex2e (in latex 2.09 compatibility mode). To get a fun-free version change the `FUN' variable to `n' on the second line (option dedicated to my friend Yuri Tschinkel). Postscript file with color illustration available on http://math.bu.edu/INDIVIDUAL/abrmovic/fibered.p